With reference to FIGS. 1 and 4, the actuation of intake and exhaust valves 12 and 14 respectively, in a 4-valve per cylinder internal combustion engine 10, particularly a diesel engine, may require the use of a valve bridge 16 due to various design constraints such as actuation type, valve location, cylinder and/or cylinder head configuration, fuel injector location, or a combination thereof. A valve bridge 16 is a device that spans the distance between and contacts two valves, either intake or exhaust, any has a contact point roughly equidistant from the centerline of both valves. The valve bridge 16 is used as a location for actuation of the valve set by a rocker arm 18.
A common issue with a valve bridge system of the type just described is that various tolerances and operating parameters such as valve length, valve seat configuration, valve spring height and rate or a combination thereof may result in one valve opening and/or closing at a different time than the other valve in a set. As a result, the profile of the cam actuator must be designed with longer and higher ramps to avoid high contact velocities between the valves 12, 14 and their respective valve seats. Such long ramps compromise engine breathing, resulting in reduced power, reduced torque and increased emissions.